Overview
A high severity vulnerability, identified as CVE-2021-47667, has been discovered in ZendTo versions 5.24-3 through 6.x before 6.10-7. This vulnerability, an OS command injection, could allow unauthorized remote attackers to execute arbitrary commands on the affected system, potentially leading to system compromise or data leakage. This issue requires immediate attention and mitigation, particularly for businesses and organizations utilizing ZendTo for file sharing and transfer, as the vulnerability could be exploited to gain unauthorized access to sensitive information.
Vulnerability Summary
CVE ID: CVE-2021-47667
Severity: Critical (CVSS: 10.0)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: Potential system compromise or data leakage
Affected Products
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Product | Affected Versions
ZendTo | 5.24-3 through 6.x before 6.10-7
How the Exploit Works
This vulnerability exists due to improper sanitization of the ‘tmp_name’ parameter in the lib/NSSDropoff.php script when a file is dropped off via a POST/dropoff request. This allows an attacker to inject shell meta-characters, which are interpreted and executed by the system. As a result, an attacker can execute arbitrary system commands, compromising the system or potentially leading to data leakage.
Conceptual Example Code
Here is a conceptual example of how this vulnerability might be exploited. In this case, the attacker sends a malicious POST request to the /dropoff endpoint with shell meta-characters in the ‘tmp_name’ parameter:
POST /dropoff HTTP/1.1
Host: target.example.com
Content-Type: multipart/form-data
--boundary
Content-Disposition: form-data; name="tmp_name"
; rm -rf /; #
--boundary--In the above example, the attacker attempts to delete all files in the system root directory. This is just a conceptual example, the actual payload would depend on the attacker’s intent and the specific system configuration.
Mitigation and Patch Information
The vendor has released a patch for this vulnerability in version 6.10-7. It is highly recommended to install this patch as soon as possible. If immediate patching is not possible, temporary mitigation measures include the use of a Web Application Firewall (WAF) or Intrusion Detection System (IDS) to detect and block attempts to exploit this vulnerability.